MAGEA9 Expression in Vocal Fold Leukoplakia and Its Enhancement of Vocal Fold Leukoplakia Epithelial Cell Proliferation, Migration, and Invasion Through the NF-kB-MMP-2/9 Pathway.

Abstract

Purpose: The expression of MAGE-A9 in vocal fold leukoplakia (VFL) tissues and the mechanism underlying its role in the malignant transformation of VFL remain unclear. This study investigated the role of MAGE-A9 in the proliferation, migration, and invasion of VFL epithelial cells as well as the underlying regulatory mechanism.

Methods: MAGE-A9 expression in VFL tissues was detected by immunohistochemistry. The CCK-8 assay, flow cytometry, and transwell assays were performed to determine the viability, cell cycle distribution and apoptosis, as well as migration and invasion, respectively, of primary cultured VFL epithelial cells. Ki67, cell cycle proteins, and proteins in the NF-kB-MMP-2/9 pathway were assessed by Western blotting.

Results: MAGE-A9 expression was detected in 54.5% (18/33) of vocal fold polyps, 48.9% (44/90) of VFLs, and 84.8% (28/33) of laryngeal cancers. Significantly higher levels of expression were found in laryngeal cancer than in vocal fold polyps and VFL tissues (P < 0.001). The expression of MAGE-A9 tended to increase with the severity of VFL dysplasia. In VFL epithelial cells, the overexpression of MAGE-A9 significantly increased the viability, proliferation, migration, and invasion of the cells and reduced the level of apoptosis. The cell cycle effects of MAGE-A9 overexpression included an increased proportion of cells in the G2 and S phases and a decreased proportion of those in the G1 phase (P = 0.002), leading to an altered G1/S phase transition. MAGE-A9 overexpression also significantly increased p-IKBα, p-p65, MMP2, and MMP9 levels while decreasing those of IKBα. All of the effects of MAGE-A9 were inhibited by treating the cells with the IκBα phosphorylation inhibitor BAY 11-7082.

Conclusion: MAGE-A9 expression tended to increase with the severity of dysplasia in VFL and was significantly higher in laryngeal cancer than in VFL. MAGE-A9 was shown to promote the proliferation, migration, and invasion of VFL epithelial cells via the NF-kB pathway and downstream targets such as MMP-2/9.